The present invention relates to electrical apparatus such as transformers and more particularly to protective devices located within the apparatus casing for interrupting the power circuit in response to an electrical fault and overload conditions. A number of systems for protecting distribution transformers from such conditions, such as fuses, have been used to provide fault current protection in combination with temperature responsive devices for providing overload protection. Most of these devices are either destructive type systems such as the fuses which must be replaced or that require opening of the transformer casing to reset or replace the device.